Mayor Ed Murray of Seattle, right, after the City Council approved a minimum wage that is more than double the federal minimum. The $15 rate is the highest among the nation’s big cities.CreditCreditTed S. Warren/Associated Press

SEATTLE — The City Council here went where no big-city lawmakers have gone before on Monday, raising the local minimum wage to $15 an hour, more than double the federal minimum, and pushing Seattle to the forefront of urban efforts to address income inequality.

The unanimous vote of the nine-member Council, after months of discussion by a committee of business and labor leaders convened by Mayor Ed Murray, will give low-wage workers here — in incremental stages, with different tracks for different sizes of business — the highest big-city minimum in the nation.

“Even before the Great Recession a lot of us have started to have doubt and concern about the basic economic promise that underpins economic life in the United States,” said Sally J. Clark, a Council member. “Today Seattle answers that challenge,” she added. “We go into uncharted, unevaluated territory.”

But some business owners who have questioned the proposal say that the city’s booming economy is creating an illusion of permanence. The fat times and the ability to pay higher wages, they warn, will not go on forever.

“We’re living in this bubble of Amazon, but that’s not going to go on,” said Tom Douglas, a prominent restaurateur in Seattle, referring to the local boom in jobs and economic growth from hiring at Amazon, the online retailer, which has its headquarters here. Mr. Douglas said the new law will inevitably result in costs being passed on to consumers. “There’s going to be some terrific price inflation,” he said.

The measure has the support of Mr. Murray, who ran last year on a pledge to raise the wage to $15 and made it one of his first priorities in office.

Cheers and jeers repeatedly erupted in the City Hall meeting room, which was packed with supporters of the plan, who often interrupted speakers in the 90-minute debate before the vote with chants.

“We did it — workers did this,” said Kshama Sawant, a socialist who campaigned for a $15 minimum wage when she was elected to the Council last year. Ms. Sawant sought to accelerate the carrying out of the measure and to strip out a lower youth wage training rate, but the council rejected her proposals.

The vote, economists and labor experts said, accentuates the patchwork in wages around the country, with places like Seattle — and other cities considering sharply higher minimum pay, including San Diego, Chicago and San Francisco — having economic outlooks increasingly distinct from those in other parts of the nation. Through much of the South, especially, the federal minimum of $7.25 holds fast.

Eight states plus the District of Columbia have already increased their minimum wages this year, the most to have done so in a single year since 2006, and at least eight other states and municipalities could put minimum wage ballot measures before voters by November. But it is the scale of ambition that is catching the attention of economists, labor leaders and business owners.

“In past rounds of minimum wage increases, proposals sought chiefly to restore the value of the minimum wage lost to inflation over the decades,” said Paul Sonn, the general counsel and program director at the National Employment Law Project, a New York-based group that supports raising the minimum wage. The increases in places like Seattle, Mr. Sonn said, go beyond playing catch-up. “The $15 proposals make real gains,” he said.

Economists who study the minimum wage are not sure of the effect of having sharply different levels — in some places, it is twice that of others. Though records are a bit uncertain, people who track minimum wage law say the range of mandated minimums, lowest to highest, is the largest it has been since a national minimum was established by Congress in 1938.

“Nobody has studied a doubling of the minimum wage — that’s outside our experience,” said Dale Belman, a professor of labor and industrial relations at Michigan State University and co-author of a coming book about the minimum wage.

Individual workers and business owners in and around Seattle are unsure of the implications. Washington State already has the highest state minimum wage in the nation, $9.32, but more than 24 percent of Seattle residents earn hourly wages of $15 or less, according to the city, and approximately 13.6 percent of Seattle residents live below the federal poverty level.

Under the plan approved on Monday, the hourly wage will rise to $15 by 2017 for employers with more than 500 workers that do not provide health insurance, and by 2018 for those large employers who do. The minimum will be phased in through 2021 for smaller employers.

In its early years, the law allows employers to include tips as part of a workers’ compensation in reaching the minimum, but that provision is phased out over time.

“The short-term side of it says it’s attractive,” said Mickey Adame, a bartender who works in Bellevue, Washington’s fifth-largest city, which is just outside Seattle, and the new $15 wage boundary. “But I think people in Seattle aren’t going to tip as much, knowing the servers are getting paid $15,” added Mr. Adame, who lives in Seattle and is trying to start a music record label called Sounder Music, for which his tip jar, he said, is crucial. “If I had to pick an answer, I would say I think I’ll make more in Bellevue.”

Ms. Sawant, in her comments to the Council and the crowd, did not take the tone of someone who was savoring a victory. The fight for workers’ rights and economic fairness, she said, is not over.

“We have fought to the last day, the last hour, against all the loopholes demanded by business,” she said. “The attempts of business to undermine $15 will continue,” she said, as would the battle to “turn the tide against corporate politics.”

She added: “$15 in Seattle is just a beginning. We have an entire world to win.”

A version of this article appears in print on , on Page A15 of the New York edition with the headline: Seattle Approves $15 Minimum Wage, Setting a New Standard for Big Cities. Order Reprints | Today’s Paper | Subscribe